ref: 59b1d9b6c40d88d3b6373993662c3bce3541f3a0 dir: /lib/std/swap.myr/
pkg std = generic swap : (a : @a#, b : @a# -> void) ;; generic swap = {a : @a#, b : @a# var t t = a# a# = b# b# = t }